1. Field of the Invention
The present invention relates to a music sound generator, more specifically, to a music sound generator suitable for imitating an effect sound when releasing a key of an acoustic piano.
2. Description of the Related Art
In an acoustic piano, a damper is used to suppress vibration of piano strings other than the time of pressing a key. When depressing the key, first, an action works and then a damper corresponding to the depressed key is released. Second, a hammer strikes the strings to generate a piano sound. When stopping the pressure on the key and returning the key to the original state, the action works in reverse, the released damper comes into contact with the strings again to suppress vibration, and the piano sound is stopped. At the time of this stop of the piano sound, the damper comes into contact with the strings being vibrated, so that a delicate string vibration sound different from the normal music sound is generated although duration of the vibration sound is short. Hereinafter, this string vibration sound will be referred to as “released key string vibration sound.”
The damper is not provided for all strings, and for strings of one and a half octaves on the high note side, no damper is provided and the strings are always released. Even in the case of strings for which a damper is provided, portions (fore strings and back strings) of the strings which are not vibrated normally are equivalent to always be in a released state regardless of the working of the damper.
Due to these released strings and frame, etc., the acoustic piano slightly resonates. Therefore, when a piano sound is generated by striking a key, a delicate resonance of the piano itself is added to the piano sound. This resonance is masked by the piano sound and cannot be heard while key pressing, however, it is understood that it remains when the key is released and the piano sound stops. This resonance will be referred to as “cabinet resonance.”
Conventionally, attempts were made to imitate a released key string vibration sound and a cabinet resonance by an electronic instrument such as an electronic piano. For example, a released key string vibration sound of a normal music sound generated by pressing a key is imitated by setting a longer attenuation time when releasing the key.
In addition, there is known a music sound generator (Japanese Published Unexamined Patent Application No. 2001-236067) which when key-off information is supplied, can deaden a main music sound being generated and generate a key-off sound instead of a released key string vibration sound or a cabinet resonance. In this music sound generator, when key-off information is supplied, characteristics of a main music sound at a pitch instructed by the key-off information are detected, and the detected characteristics of the main music sound are set as characteristics of a key-off sound. This music sound generator determines characteristics of a key-off sound according to the time from key-on to key-off.
However, a sound generated when releasing a key of an acoustic piano contains an element that is not generated normally while sounding, so that even if the attenuation time when releasing the key is set to be longer, the characteristic sound when releasing the key cannot be sufficiently reproduced. In addition, in the method described above in which a key-off sound is newly generated when releasing the key, a new system for generating a music sound in response to key-releasing is necessary. Furthermore, to maintain the continuity of the normal music sound, the key-pressing time and normal music sound volume, etc., must be managed and effect sounds generated responsively must be controlled, so that the control becomes complicated and enormous in scale.